A group of powerful legal scholars are trying to make an end run around the Constitution.

The George Zimmerman saga came to an end last weekend when a jury of six Florida women found the neighborhood-watch captain not guilty in the shooting death of Trayvon Martin. But even before the 15-month legal process had begun last year, the United Nations' top human-rights official had rendered a guilty verdict—against Mr. Zimmerman and the entire U.S. judicial system.